Two unknown lights seen in the sky at separate times during the same night.

Earlier in the night around midnight I witnessed out the window what looked like a very very bright star that was flickering like crazy like one does when it's dying. Eventually it started moving very slowly and then picked up in speed until it went out of view and I lost it due to being on the opposite end of a huge building and in the middle of working anyway. Later in the night when I was done working around 1:30AM me and my coworker went up on the roof and he said he "Hey what's that?" and pointed but I couldn't figure out where he was pointing and by the time I walked back to where he was to see where he was pointing, which was only a matter of seconds, it was gone. He said he saw some kind of diamond shaped object that was moving like a plane that was dark orange and had an orange glow to it and left a trail and disappeared along with it's trail as it moved into the aura of the city lights. I could of tried to take a picture of it with my camera on! my phone had I of seen it in time but unfortunately this wasn't possible.